Sunday

Most science papers don’t begin with a description of psi, those “anomalous processes of information or energy transfer” that have no material explanation. (Popular examples of psi include telepathy, clairvoyance and psychokinesis.) It’s even less common for a serious science paper, published in an elite journal, to show that psi is a real phenomenon. But that’s exactly what Daryl Bem of Cornell University has demonstrated in his new paper, “Feeling the Future: Experimental Evidence for Anomalous Retroactive Influences on Cognition and Affect,” which was just published in The Journal of Personality and Social Psychology.

Bem’s experimental method was extremely straightforward. He took established psychological protocols, such as affective priming and recall facilitation, and reversed the sequence, so that the cause became the effect. For instance, he might show students a long list of words and ask them to remember as many as possible. Then, the students are told to type a selection of words which had been randomly selected from the same list. Here’s where things get really weird: the students were significantly better at recalling words that they would later type.

Or consider this experiment, which is a direct test of precognition. Bems provided the following instructions to subjects:

This is an experiment that tests for ESP. It takes about 20 minutes and is run completely by computer. First you will answer a couple of brief questions. Then, on each trial of the experiment, pictures of two curtains will appear on the screen side by side. One of them has a picture behind it; the other has a blank wall behind it. Your task is to click on the curtain that you feel has the picture behind it. The curtain will then open, permitting you to see if you selected the correct curtain. There will be 36 trials in all. Several of the pictures contain explicit erotic images (e.g., couples engaged in nonviolent but explicit consensual sexual acts). If you object to seeing such images, you should not participate in this experiment.

The location of the image was selected at random by the computer, which means that students should have correctly guessed the location of the pornography 50 percent of the time. However, it turned out that over 100 sessions, the subjects consistently performed above chance, and correctly located the porn 53.1 percent of the time. Interestingly, their hit rate on “non-erotic pictures” did not deviate from chance. (They found neutral pictures, for instance, 49.8 percent of the time.)

The power of Bem’s paper is cumulative. In total, he describes the results of nine different experiments, conducted on more than 1000 subjects. All of the experiments revealed slight yet statistically significant psi anomalies, with an average effect size of 0.21 across all experiments.

However, the real contribution of this paper isn’t even these statistically significant results. Instead, it’s Bem’s attempt to create rigorous, well-controlled tests of psi that can be replicated by independent investigators. Because here is the dirty secret of anomalous phenomena like telepathy and clairvoyance: They’ve been demonstrated dozens of times, often by reputable scientists. (Bem is an extremely well-respected psychologist, best known for his work on self-perception.) Why, then, do serious scientists dismiss the possibility of psi? Why do rational people assume that parapsychology is bullshit? Because these exciting results have consistently failed the test of replication.

Consider the story of Adam Linzmayer. In the spring of 1931, Linzmayer, an undergraduate at Duke University, began participating in an experimental test of extra-sensory perception, or ESP. The study was led by the psychologist Joseph Banks Rhine and revolved around the Zener deck, a special set of cards featuring five different symbols. The test itself is straightforward: A card is drawn from the deck and the subjecte= is asked to guess the symbol. While most of Rhine’s subjects performed in the neighborhood of random chance – they guessed about 20 percent of the cards correctly – Linzmayer averaged nearly fifty percent during his initial sessions. Furthermore, these “guesses” led to several uncanny streaks, such as when he correctly guessed nine cards in a row. The odds of this happening by chance are about one in two million. Linzmayer did it three times.

Although Rhine was studying ESP, he thought of himself as a skeptical scientist, eager to test the strange claims of psychics and magicians. At first, Rhine simply assumed that Linzmayer was cheating, and that he’d had found some way to peek at the cards. This hunch was quickly disproven, however, as Linzmayer’s guesses far exceeded random chance even when facing away from the deck. And so, over the next few weeks, the scientist continued testing the student, repeating the same tedious task under slightly different conditions. (During a three-day binge before finals, Linzmayer guessed more than 15,000 cards, with a 40 percent accuracy rate.)

According to Rhine, the most astonishing demonstration of Linzmayer’s talent occurred in his car, after he’d taken the student for a relaxing drive. It was here, in this setting of “easy informality” – the idling engine had a soothing effect – that Linzmayer correctly guessed fifteen cards in a row. (The probability of such a run occurring by accident is approximately one in 30 billion.) After this session, Rhine was finally convinced that Linzmayer was capable of clairvoyance. “No conceivable deviation from probability, no ‘streak of luck’ which either of us had ever heard could parallel such a sequence of unbroken hits,” Rhine later wrote. “We both knew that the thing Linzmayer had just done was virtually impossible by all the rules in the book…But he had done it.” (For a more detailed description of these experiments, see Rhine’s New Frontiers of the Mind.)

Rhine documented this landmark event in his notebook, and prepared several papers for publication. But then, just as the scientist began to grow confident in the existence of ESP, the clairvoyance disappeared. Linzmayer lost his spooky talent. Between 1931 and 1933, the student guessed the identity of another 50,000 cards, except his success rate was now a meager 22.4 percent, or barely above average. Rhine was forced to conclude that the student’s “extra-sensory perception ability has gone through a marked decline.”

A similar trend occurred with other Rhine subjects, and with nearly every other confirmed demonstration of psi. As a result, the phenomenon was never taken seriously, despite the fact that it had been repeatedly demonstrated in the lab.

And this is why Bem’s paper is so important: It provides the first testable framework for the investigation of anomalous psychological properties. Unlike the Zener deck, for instance, these tests build upon well-known experimental paradigms, and minimize the contact between the experimenter and the subject. The data collection was automated and accurate; the paper passed peer-review. (Charles Judd, who oversaw the review process at JPSP, said: “This paper went through a series of reviews from some of our most trusted reviewers.”) Only time will tell if the data holds up. But at least time will tell us something. Bem ends the paper with a reference to Lewis Carroll:

Near the end of her encounter with the White Queen, Alice protests that “one can’t believe impossible things,” a sentiment with which the 34% of academic psychologists who consider psi to be impossible would surely agree. The White Queen famously retorted, “I daresay you haven’t had much practice. When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast.”